diff --git a/src/pretix/base/models/waitinglist.py b/src/pretix/base/models/waitinglist.py
index 29fb636ae9..ca582a3511 100644
--- a/src/pretix/base/models/waitinglist.py
+++ b/src/pretix/base/models/waitinglist.py
@@ -87,7 +87,7 @@ class WaitingListEntry(LoggedModel):
             if self.variation
             else self.item.check_quotas(count_waitinglist=False, subevent=self.subevent, _cache=quota_cache)
         )
-        if availability[1] < 1:
+        if availability[1] is None or availability[1] < 1:
             raise WaitingListException(_('This product is currently not available.'))
         if self.voucher:
             raise WaitingListException(_('A voucher has already been sent to this person.'))
diff --git a/src/pretix/base/services/waitinglist.py b/src/pretix/base/services/waitinglist.py
index 8a444f4638..90a60545d8 100644
--- a/src/pretix/base/services/waitinglist.py
+++ b/src/pretix/base/services/waitinglist.py
@@ -1,3 +1,5 @@
+import sys
+
 from django.dispatch import receiver
 
 from pretix.base.models import Event, User, WaitingListEntry
@@ -41,7 +43,7 @@ def assign_automatically(event_id: int, user_id: int=None, subevent_id: int=None
                 if wle.variation
                 else wle.item.check_quotas(count_waitinglist=False, _cache=quota_cache, subevent=wle.subevent)
             )
-            if availability[1] > 0:
+            if availability[1] is None or availability[1] > 0:
                 try:
                     wle.send_voucher(quota_cache, user=user)
                     sent += 1
@@ -52,7 +54,7 @@ def assign_automatically(event_id: int, user_id: int=None, subevent_id: int=None
                 for q in quotas:
                     quota_cache[q.pk] = (
                         quota_cache[q.pk][0] if quota_cache[q.pk][0] > 1 else 0,
-                        quota_cache[q.pk][1] - 1
+                        quota_cache[q.pk][1] - 1 if quota_cache[q.pk][1] is not None else sys.maxsize
                     )
             else:
                 gone.add((wle.item, wle.variation))
diff --git a/src/tests/base/test_waitinglist.py b/src/tests/base/test_waitinglist.py
index af8eb84cf4..a244caf09e 100644
--- a/src/tests/base/test_waitinglist.py
+++ b/src/tests/base/test_waitinglist.py
@@ -99,6 +99,22 @@ class WaitingListTestCase(TestCase):
             'foo7@bar.com', 'foo8@bar.com', 'foo9@bar.com'
         ]
 
+    def test_send_auto_quota_infinite(self):
+        self.quota.variations.add(self.var1)
+        self.quota.size = None
+        self.quota.save()
+        for i in range(10):
+            WaitingListEntry.objects.create(
+                event=self.event, item=self.item2, variation=self.var1, email='foo{}@bar.com'.format(i)
+            )
+            WaitingListEntry.objects.create(
+                event=self.event, item=self.item1, email='bar{}@bar.com'.format(i)
+            )
+
+        assign_automatically.apply(args=(self.event.pk,))
+        assert WaitingListEntry.objects.filter(voucher__isnull=True).count() == 10
+        assert Voucher.objects.count() == 10
+
     def test_send_periodic(self):
         self.event.settings.set('waiting_list_enabled', True)
         self.event.settings.set('waiting_list_auto', True)